TABLE 1.

Oxygen evolving activity of sulfate-treated PSII at pH 6.0 and 7.5

10 mM Ca+2	15 mM Cl−	pH 6.0*	pH 7.5†
—	—	60 ± 30	30 ± 10
+	+	460 ± 60	240 ± 3
—	+	370 ± 60	200 ± 20
+	—	46 ± 7	9 ± 1

Oxygen evolving activity measured at 25°C and listed with units of μmol O₂ (mg chl-h)⁻¹ (24). Values are reported ±1 standard deviation (SD). All measurements are an average of at least three individual experiments. Each measurement performed with 1 mM ferricyanide and 0.5 mM DCBQ.

^*Conditions were 400 mM sucrose and 50 mM MES-NaOH (pH 6.0).

^†Conditions were 400 mM sucrose and 50 mM HEPES-NaOH (pH 7.5).